Seizures and Seizure Planning Flashcards
what are one of the most common neurological conditions seen in veterinary practice?
seizures
how many dogs present with seizures each year?
1 in 125
in what animals are seizures most commonly seen?
dogs but can be seen in cats
if seizures are seen in cats what is the usual cause?
usually secondary to another condition
what are the key considerations that must be made about an owner when their pet has a seizure?
it can be very distressing for the owner especially the first one as they don’t know what is going on
how do neurons transmit information in the normal brain?
through chemical and electrical signals
what are interneurons?
large group of inhibitory cells which regulate the neurons in the brain
how is a seizure caused?
balance between excitatory and inhibitory input is altered leading to hypersynchronisation of neurons and so a seizure
define hypersynchronisation
The excessive synchronization of the firing of neurons that leads to seizures
what is a seizure?
an abnormal, uncontrollable, hypersynchronus electrical activation of a large group of neurons which may produce convulsions, minor physical signs, cognitive disturbances or a combination of symptoms
what is an isolated seizure?
lasts less than 5 mins and animal fully recovers after
what is a cluster seizure?
2 or more seizures within a 24 hour period with complete recovery in between
what type of seizure is a neurological emergency?
status epilepticus
describe status epilepticus
seizure lasting longer than 5 minutes
2 seizures without complete recovery in between (so may seem continuous)
why is status epilepticus dangerous?
brain damage will occur and worsen the longer the seizure goes on
what are the 2 main types of seizure?
partial or focal
generalised (tonic / clonic)
what part of the brain is affected in a partial or focal seizure?
asymmetric - only one side
what are the signs of partial / focal seizures?
facial twitching
hypersalivation
behavioural changes
consciousness maintained
what are the 2 types of partial / focal seizure?
simple
complex
what is the difference between a simple and complex focal / partial seizure?
in simple there is no change in mentation whereas in complex change in mentation is seen
what areas of the brain are involved in generalised (tonic/clonic) seizures?
bilateral cerebral hemisphere involvement
describe what happens during a generalised (tonic/clonic) seizure
autonomic signs (urinate and defecate) loss of consciousness
what are the 3 phases of generalised (tonic/clonic) seizures?
pre-ictal
ictal
post-ictal
how long does the pre-ictal phase last for?
minuites
when does the pre-ictal phase occur?
before the seizure happens
what are the signs of the pre-ictal seizure phase?
may be subtle
behaviour changes
altered mentation
attention seeking behaviour
when does the ictal phase occur?
the actual seizure
what happens during the ictal phase?
loss of consciousness
muscle contraction
urination / defecation
when does the post-ictal phase occur?
after the seizure
how long does the post ictal phase of a seizure last?
minutes to days
depends on individual
what are the signs of the post-ictal phase?
abnormal neurological signs which may be subtle or marked
what are the 2 main extracranial causes of seizures?
toxins
metabolic
what are the main toxins which cause seizures?
methaldehyde (slug bait) ethylene glycol (antifreeze) permethrin (cats) pesticides Ivermectin (collies) human drugs
what are the metabolic causes of seizures?
portosystemic shunt
hypoglycaemia
hypocalcaemia
why can a postosystemic shunt lead to seizures?
change in blood flow will collect toxins from vessels that have been bypassed before shunt placed that are then moved around the body
what are the 2 main intracranial causes of seizures?
structural
functional
what are the structural causes of seizures?
brain tumor
inflammation
hydrocephalus
what is the functional cause of seizures?
idiopathic epilepsy
what is the most common cause of seizures?
idiopathic epilepsy
what age are animals that present with idiopathic epilepsy?
6 months to 6 years
what signs will suggest that an animal has idiopathic epilepsy?
recurrent single seizures normal inter-ictal neuro exam normal metabolic investigation normal brain MRI normal CSF (if tap taken)
how is idiopathic epilepsy / seizure cause diagnosed?
history blood tests MRI scan with contrast CSF analysis video assessment of seizure monitoring and recording (e.g. seizure diary) retinal exam blood pressure (if possible)
what information can be gained when taking a history of a patient with seizures?
is it a true seizure
any history of toxin ingestion, head trauma or meidacation
what blood tests will be used to diagnose the cause of seizures?
haematology
biochem
fasted blood glucose
pre and post prandial bile acids
what contrast is used in MRI scans of the brain?
gadolinium
what is needed when preparing for CSF tap?
clip and surgical prep
what position must the animals head be held in for a CSF tap?
flexed downwards
why is important to know the difference between seizures and seizure mimics/
testing and mediaction are different